They can be described as consisting of two skins separated by a hollow space cavity.
Cavity wall insulation diagram.
Cavity wall insulation explained.
One function of the cavity is to drain water through weep holes at the base of the wall.
Cavity wall insulation costs and savings.
Many cavity walls can be insulated by injecting insulation material into the cavity from the outside.
A specialist company will drill holes in the outside walls inject insulation through the holes and then seal them with cement.
While rated differently these two types of insulation are close enough in thickness that they can both fit into modern two by four wall systems.
In most wall applications you will use r 13 or r 15 kraft faced fiberglass insulation rolls for these two by four stud walls.
These pockets are more efficient at reducing heat transfer by convection than the big air cavity was.
They make it impossible for large convection currents to be set up.
A cavity wall is a type of wall that has a hollow center.
The skins typically are masonry such as brick or cinder block masonry is an absorbent material that can slowly draw rainwater or even humidity into the wall.
Cavity wall insulation normally takes around two hours to install but this depends on the size of the house and other factors such as ease of access.
Installing cavity wall insulation can save up to 245 per year on your energy bills.